Adjustable piston



v 3.5 in automobiles and Patented Aug. 25, 1931 DELHER F. CRANDALL, OE SEATTLE, WLEa-SHINGTON ADJUSTABLE PISTON Application filed November 19, 1927, Serial No. 234,519. Renewed June 2, 1931.

This invention relates to trunk pistons such as are used for internalcombustion engines, and particularly to a piston formed in two sections, and the general object of this invention is to provide a piston formed in two sections, wherein one of said sec tions is adjustable so as to do away with the replacement of worn or slapping pistons with new pistons until such time as the cyl- 1Q inders are too badly Worn for the adjustable piston to take care of the difiiculty.

A further object is to provide a construction of this character having screws which hold one section of the piston to the other,

'1 these screws being adjustable so as to prevent the expansion of the piston beyond a maximum diameter, and provide internal springs urging the sections of the adjustable piston away from each other, tothus take up wear and permit the piston to conform to the cylinder walls.

My invention is illustrated in the accompanying drawings, wherein Figure 1 is an elevation of a piston constructed in accordance with my invention, the piston at the junction of the two sections being broken away;

Figure 2 is a face view of the piston looking toward the removable section;

Figure 1;

Figure 4 is an inside face view of the removable section.

Nearly all trunk pistons such as are used other internal combus tion engines wear on one side only and usually just below the ring grooves. It is the general practice of automobile mechanics to peen loose pistons to make them fit the cylinders or to use springs behind the rings. My invention does away with this necessity of peening the pistons or using the rings.

As shown in the accompanying drawings, the piston is composed of two sections 10 and 11. The section 10 is circular at its upper end and is grooved for the piston rings, as at 12. At its extreme lower end the skirt 13 of the piston is also circular. In other words, the section 10 consists of a body having the form of a trunk piston but Figure 3 is a section on the line 3-3 of cut away at ii. The ;--ciiion1(.l is formed with the bosses 1:3 for the. wrist pin 16 as usual, these bosses opening upon the exterior face of the piston usual to permit the insertion of the pin. Each of these bosses terminates along the edge 17 of the section 10.

Coacting with the section 10 is the section 11, as before stated. This is arcuate in plan view and its between the upper portion of the section 10 and the lower portion thereof,'0r in other words its in the opening 14;. This section is also formed with internal bosses 18 which, when the sections are in place, abut against the bosses 15. There #35 are preferably bosses 18- at the top of the sections and bosseslS at the bottom of the section, and the lower end of the skirt 13, is also formed with bosses 19 against which the bosses l8 abut. Each oi the bosses 18 is formed with a countersink :0 extending inward from the face of the piston, this (roan tersunk opening being for the reception of a'headed screw 21. When the screw 21 is in place, the head is entirely concealed within the countersunk opening 20. The bosses 1.5 and 19 are formed with like openings inter'iorly screw-threaded for the reception of the screws 21. Itwill be understood that the countersunk openings 20 are not screwthreaded but that the screw recesses 22 in the section 10 are internally screw-threaded:

It will be obvious that by turning up the screws 21, the two sections may be drawn tightly against each otherv against any out- Ward movement. Preferably, however, these screws are not turned tight home but a slight space is left at the joint at the opposite edges of the opening '14. Each of the bosses 18 and each of the corresponding bosses 15 are formed to provide confronting springsreceiving sockets 23 within which coiled compression springs 24: are placed which act, of course, to urge the sections away from each other to an extent permit- 86 ted by the adjustment of the screws 21.

With the construction which has been described, wear can be taken up by adjusting the section 11 with the adjusting screws 21 to a running fit. The adjusting screwsqict as a back stop for the section 11 but the quarter-inch compression springs 24 will allow the sections of the piston to conform to the cylinder walls. If necessary, springs may be inserted between the piston sections at the lower end of the piston if desired.

This piston is designed to have a plug fit, or in other words the piston is fitted to or 'made the same size as the cylinder, and as the piston is worked orrun it makes a snug fit and will last much longer than the ordinary piston. The two sections of the piston are adjusted to an extreme diameter by the screws 21. The springs 24 will force the two sections out, therefore, to this extreme diameter but in case of excessive heat or uneven cylinder walls or like incidents, the sections will move inward with relation to each other. The adjusting screws will not allow the piston to have any drag or friction on the cylinder walls. Preferably the piston is made of white metal or cast iron and the section 11 is machined to a sliding fit within the opening 14 so as to allow the top portion of the section 11 to move inward or outward with uneven cylinder walls.

In practice, the piston can be taken out and adjusted to the proper size with micrometers and then placed back in the motor. A piston of this type will do away with the necessity of peening the piston to eliminate piston slaps, do away with slotted or cut out pistons or with. the necessity of using springs ehind the rings. The piston will not cause any undue friction, inasmuch as the adjusting screws hold the piston to an extreme diameter, while the compression springs permit of expansion of the pistons without affecting the exterior diameter of the piston at all. r

I claim A trunk piston formed in two sections, one of the sections including the head of the piston and having piston ring grooves and being formed to provide the skirt of the piston, the skirt being provided with inwardly projecting bosses having longitudinally fiat faces and formed to provide wrist pin bearings, said skirt being cut away to provide an opening from a point adjacent one of said bosses to a point adjacent the other of said bosses and extending from a point just below the piston ring grooves nearly to the lower end of the piston, the last named section having bosses on its inner face adjacent its margins bearing against and confronting the bosses of the first named section, the bosses of the first named section having countersunk, screw-threaded passages extending inward from the outer face of the section and the bosses of the second named section having screw-threaded passages alining with the countersunk passages, screws having heads loosely disposed in the counter-sunk passages and having threaded signature.

DELMER F. CRANDALL. 

